Data transmission telemonitoring equipment and system

Abstract

A telemetering system for a data transmission line having a sequence of repeaters controls sequential operation from a centralized single supervisory terminal. The supervisory terminal sends an interrogation signal forward to a first repeater which sends back an answer signal relating to the status of that repeater and also sends the interrogation signal forward to the second repeater. In addition, status answer signals received from said subsequent repeaters in the sequence are transmitted backward through the repeater chain to the supervisory terminal. Thus, each repeater acts on the telemetering channel as a bidirectional repeater, repeating forwardly the interrogation signal and repeating backwardly its answer and the answer of subsequent repeaters in the sequence. Eight status parameters are detected at each repeater and monitored at the supervisory terminal. The supervisory terminal includes a clock generator, a receiver-transmitter interface, a microprocessor for processing repeater status information, a display, a selector and a bus interface. Each repeater includes a local oscillator, an error detector, an error counter, a detector of the error counter status, an answer signal generator, an answer transceiver, an interrogation transceiver and an automatic monitoring unit.

What I claim is: 
     
       1. In a data transmission system of the type in which plural transceiver-type repeaters are spaced in sequence from 1 to n along a data transmission line, a method of monitoring the status of the repeaters comprising the steps of: generating an interrogation signal only at a single supervisory terminal and transmitting the interrogation signal along said transmission line;   in response to receiving the interrogation signal at repeater i in said sequence, where i is a number between 1 and n, transmitting status information relating to repeater i back to said supervisory terminal from repeater i, and transmitting said interrogation signal from repeater i to repeater i+1 in said sequence along said transmission line; and   monitoring and displaying only at said single supervisory terminal the status information transmitted by all of said repeaters;   whereby each of the first n-1 repeaters in said sequence receives the interrogation signal successively and transmits information reflecting its status back to the supervisory terminal and transmits the interrogation signal on the transmission line to the next repeater in said sequence.   
     
     
       2. The method according to claim 1 further including the step of: at the nth repeater in said sequence, in reponse to receiving said interrogation signal, transmitting status information relating to the nth repeater along with an end of channel identification signal back to said common supervisory terminal.   
     
     
       3. The method according to claim 1 further comprising the step of: at repeater i, in response to receiving status information from subsequent repeaters in said sequence, transmitting the received status information back to said supervisory terminal.   
     
     
       4. The method according to claim 1 further comprising the step of: only at said supervisory terminal, supplying output signals representing received repeater status information to a printer.   
     
     
       5. The method according to claim 1 further comprising the step of: at said supervisory terminal, processing the received status information from the repeaters in: an automatic mode wherein the supervisory terminal provides as its first output information the "worst" repeater status for the interrogated system along with an indication of the error rate for that repeater, whereby an operator is able to successively carry out a survey of the other repeaters and preset a fixed threshold for the error rate so that the first repeater in which that error rate is exceeded may be identified;   a manual mode wherein the operator actuates the system so that for each repeater the supervisory terminal monitors the detected error rate, whether or not the predetermined error rate has been exceeded, and accumulated errors; and   an automatic test mode wherein the supervisory terminal provides an interrogation enable condition and introduces errors into the data signal so that the error detection and counting capability of each repeater may be checked.     
     
     
       6. The method according to claim 1 wherein the status information transmitted back to the supervisory terminal from each repeater includes information relating to at least five separate operating parameters of that repeater. 
     
     
       7. The method according to claim 6 wherein the operating parameters include: error rate lower than 1/1,000 counter overflow; and number of errors. 
     
     
       8. The method according to claim 7 wherein the number of errors parameter is subdivided into the following parameters: the number of errors is in the range of 64-640; the number of errors is in the range of 8-63; the number of errors is in the range of 4-7; the number of errors is in the range of 1-3; and the number of errors is 0. 
     
     
       9. The method according to claim 6 further comprising the step of: at each repeater, detecting and counting errors and measuring the error rate.   
     
     
       10. A telemonitoring system for a data transmission line comprising: a plurality of transceiver repeaters interposed in sequence along said transmission line;   a single supervisory terminal disposed in said transmission line before the first repeater in said sequence; said supervisory terminal having a means for receiving status information, and a means for displaying status information;   generator means at said supervisory terminal for generating an interrogation signal;   transmitter means at said supervisory terminal for transmitting said interrogation signal to the first repeater in said sequence along said transmission line;   receiver means at each repeater for receiving said interrogation signal;   status transmitter means at each of said repeaters for transmitting repeater status information on said transmission line toward said supervisory terminal in response to receiving said interrogation signal;   transmitter means at each of repeaters 1 through n-1 for transmitting said interrogation signal to the next repeater in said sequence in response to receiving the interrogation signal from the immediately preceding repeater in said sequence;   transmitter means at said repeater n for transmitting an end-of-channel signal on said transmission line back toward said supervisory terminal in response to receiving said interrogation signal; and   means located only at said supervisory terminal for monitoring and displaying status information received from said repeaters.   
     
     
       11. The system according to claim 10 further comprising means located only at said supervisory terminal for supplying output signals representing received repeater status information in a form usable by a printer. 
     
     
       12. The system according to claim 10 further comprising means located only at said supervisory terminal for processing the received status information from the repeaters in: an automatic mode, wherein the supervisory terminal displays as its first piece of information the "worst" repeater status in the interrogated system along with the error rate for that repeater, whereby an operator is able to successively carry out a survey of the other repeaters and preset a fixed threshold for the error rate to permit an indication of the first repeater to exceed the fixed threshold;   a manual mode, wherein the operator actuates the system for each repeater to detect the error rate, to detect exceeding the pre-established error rate and to accumulate detected errors; and   an automatic test mode, wherein the supervisory terminal provides an interrogation enabling signal for a short period of time during which entry of violations of the available data signal, without alteration of the data signal content, are inserted to permit checking the error detection and counting capability at the various repeaters.   
     
     
       13. The system according to claim 10, wherein the status information transmitted back to the supervisory terminal from each repeater includes information relating to at least five separate operating parameters of that repeater. 
     
     
       14. The system according to claim 13, wherein said operating parameters include: error rate lower than 1/1,000; counter overflow; and number of errors. 
     
     
       15. The system according to claim 14, wherein the number of errors parameter is subdivided into the following parameters: the number of errors is in the range of 64-640; the number of errors is in the range 8-63; the number of errors is in the range of 4-7; the number of errors is in the range of 1-3; and the number of errors is 0. 
     
     
       16. The system according to claim 13 further comprising, at each repeater, means for detecting and counting each error and measuring the error rate.